"As the gap between [Donald] Trump and [Hillary] Clinton has shrunk, it's made life a little easier on some of our incumbent senators running for re-election," he told reporters, as The Hill reported.

Noting Trump's polling gap with Hillary Clinton has been tightening, Corney said he hopes the trend holds up, "because I think no matter what happens, I would like to have the majority in the Senate to help determine what the agenda would be," The Hill reported.

"If the election were held today I'd feel pretty good about it, but obviously the election isn't today," he added.

Republicans are defending 24 Senate seats in November, including some in purple states previously won by President Barack Obama, The Hill noted. Democrats need to win back five seats—or four if they also retain the White House—to regain control of the Senate.

Polls released Sunday found GOP Sens. John McCain of Arizona, Johnny Isakson of Georgia, and Kelly Ayotte of New Hampshire, as well as Rep. Joe Heck, who is running for the Senate from Nevada, all ahead in their races.